The subject invention relates to a catheter and introducer needle assembly that includes a needle shield that will safely shield the sharp distal tip of the introducer needle after the needle has been used to insert the catheter into a patient. In addition, this invention includes a mechanism to connect the needle shield to the catheter until the sharp distal tip of the introducer needle is covered by the needle shield.
Catheters, particularly intravascular (IV) catheters, are used for infusing fluid, such as normal saline solution, various medicaments and total parenteral nutrition, into a patient, withdrawing blood from a patient or monitoring various parameters of the patient's vascular system. Peripheral IV catheters tend to be relatively short, and typically are on the order of about two inches or less in length. The most common type of IV catheter is an over-the-needle peripheral IV catheter. As its name implies, an over-the-needle catheter is mounted over an introducer needle having a sharp distal tip. At least the distal portion of the catheter tightly engages the outer surface of the needle to prevent peelback of the catheter and thus facilitates insertion of the catheter into the blood vessel. The catheter and the introducer needle are assembled so that the distal tip of the introducer needle extends beyond the distal tip of the catheter with the bevel of the needle facing up away from the patient's skin.
The catheter and introducer needle assembly is inserted at a shallow angle through the patient's skin into a blood vessel. There are many techniques for inserting such a catheter and introducer needle assembly into a patient. In one insertion technique, the introducer needle and catheter are inserted completely into the blood vessel together. In another technique, the introducer needle is partially withdrawn into the catheter after the initial insertion into the blood vessel. The catheter is then threaded over the needle and inserted completely into the blood vessel.
In order to verify proper placement of the catheter in the blood vessel, the clinician confirms that there is flashback of blood in a flashback chamber. The flashback chamber is typically formed as part of the needle hub. Once proper placement of the catheter into the blood vessel is confirmed, the clinician applies pressure to the blood vessel by pressing down on the patient's skin over the blood vessel distal of the introducer needle and the catheter. This finger pressure occludes or at least minimizes further blood flow through the introducer needle and the catheter. The clinician then withdraws the introducer needle, leaving the catheter in place, and attaches an appropriate device to the catheter. Such a device can include a fluid delivery device, a PRN, a deadender cap or a blood pressure monitoring probe. Once the introducer needle is withdrawn from the catheter, the introducer needle is a “blood contaminated sharp” and must be properly handled.
In recent years, there has been great concern over the contamination of clinicians with a patient's blood and a recognition that “blood contaminated sharps” must be disposed to avoid an accidental needle stick. This concern has arisen because of the advent of currently incurable and fatal diseases, such as Acquired Immunosuppressive Deficiency Syndrome (“AIDS”), which can be transmitted by the exchange of body fluids from an infected person to another person. Thus, contact with the body fluid of an AIDS infected person must be avoided. As noted above, if an introducer needle has been used to place a catheter in a blood vessel of an AIDS infected person, the introducer needle, via its sharp distal tip, is a vehicle for the transmission of the disease. Although clinicians are aware of the need to properly handle “blood contaminated sharps”, unfortunately in certain medical environments, such as emergency situations or as a result of inattention or neglect, needlesticks with a contaminated introducer needle still occur.
As a result of the problem of accidental needlesticks by “blood contaminated sharps”, various needle shields have been developed. Generally, such needle shields work for their intended purpose but could be improved. For example, some needle shields are bulky, difficult to use, require special features or techniques to be operative, or may leave the sharp distal tip exposed after use until the clinician manually activates the needle shielding mechanism.
In addition, some of these needle shields can be easily disconnected from the catheter hub before the needle shield covers the sharp distal tip of the introducer needle. A mechanism to avoid this premature disconnection is a plurality of fingers longitudinally extending from the needle shield with tabs extending radially inwardly from the fingers that engage the flange at the proximal end of the catheter hub. The fingers and tabs hold the needle shield to the catheter. The configuration of the fingers and tabs is designed such that the force needed to overcome the engagement between the fingers and tabs and the catheter hub is greater than the typical force needed to move the introducer needle proximally into the needle shield. However, once the introducer needle has been fully withdrawn into the needle shield, the clinician can exert a greater proximally directed force to remove the needle shield from the catheter hub. Thus the needle shield remains engaged with the catheter until the introducer needle has been completely removed from the catheter and is safely shielded in the needle shield. Unfortunately, this configuration does not consistently ensure that the needle shield remains connected to the catheter hub until the introducer needle is locked in the needle shield. This may be undesirable because the contaminated needle could then be exposed increasing the chances for an accidental needlestick.